Telephone system



w. P. ANDRICK.

TELEPHONE SYSTEM. APucA Tlou man sspnzs, 1912.

Patented Mar. 16, 1920.

' In var) for: Wa/Mce F. Andr/ck,

calling station with the conductors.individual.

E PATENT comrAivY; INCORPORATED, or srt yonx, N., 3. A CCRPORATIONIOFNEW-YORK? TELEPHONE sY s'riaivn To all mama may] comm Be it lmown'thatal; \VALLA EP;

Jamaica, Long-"Island; in the county of followingis a'full, clearyeoncise, and exact description. 1 1 O toms,- and more particnlarly to' intercom- This invention relates to" telephone sysnmnicating telephone systems provided with aim-11111; eircu-itextend ing to a central office Band inliltipled to each ofthe 1nterc0inmun1-' catingstations comprising" the system."

. In accord a'noe withthisinvention there is provided a bridge? for 1 holdingithe trunk circuit. which may substituted*fo'rfthe answering tele'phonei' set; such substitution being Controlled by a dili'ere-ntia-lrelay, the

cnergization and deenergization o'fiiyhieh is controlled by a local circuitrelay and afrelay in circuit Witli'the trnnk'f? '3 '7 For -a more complete understanding of this invention reference should be had to the-"following description considered in con-1' nection with'the accompany ng -,draW1ng.

stations con'iprising the system, only two of which-A andfBe-are shoyvn. in the draw- ;ing; Each of the} stations of the system is provided with the usual telephone set; a trunk answeringkey T for oonnecting'thetelephone set Witlrthe trunk-circuit; a local :mswering key- L for connecting the telephone set with conductors of the intercom municating system individual tov the particiilar station; and with the usual keys '(2 and "*3 being shownat station A and and 3'at;

station 13') which are individual to' other stations of the-system and which are em ploved for connecting the telephone set at a to any calledl station of the systern g Each of the keys is: of the-locking t pe,- which vSriei iif ieation of Letters Pat ent.

7 ANnrLIoK; a citizen ot'the" United States, resldlngat wli'e'ndepressed is locked in depressed positionby' a springpressed'latehplate'16. If'

1 w L'LAoE r. AIK Tb RI CK OF JAMAiQAQ NEW YORK, AiSSiGIiTQit.lQQ WES TER EL cT mo V Patented Ma1'.16,l1920. Application fiieas temb'e' 25,1917. se1e1nNa.-193-,f1mr

a key is'loeked in depressed position, when H ,a seeon'dTkey isdepressed tlie first key will thereby-be released'and restored to normal" -pos1t1on'. Each station is provided'withza ringing key R, of the non-lockii g type which is employed in signaling between the to the depressioi'rof the rlnglng or signaling trunk circuit a holding bridge Z/Z; fjeomposed of a non-inductive'resistanceivhich A The jobject of this invention to provide an' in'ip'rox' ed iholdi-ngfniean's for the trunk.

circuit by means of which the, trunk circnit may'be held hile the original answering}. station is communicatin ii-'ith anothersta ,jaonerm syste1n..--

may be substituted for any oneof theitelephone sets. A differential relay '8 controls key I H,I of the nonflocking type, located {ati station A, cooperates with the relay "10' to various stations, there bei'ngateachstation a signalingdev ce'or belll'i' which. responds i cause the energization of difi'erenti z tlirel'ay 8. While station TA is the only "one-shown;

equipped with a holding key, stilltheleads controlled 'byjthiskey may be 'niultipled to V v as manystations' as desired, andsii'nilari holding keys provided threat. Thetrunk I answering keys "T' provided ati'the various stations cooperate with therelays' 9 an'dlO from the trunk circuit;

Referring now .to the operatio'n l of; the

system: -shoW1'1' in v the drawings, it will: be, assumed 'that theoperator at the central office not shown) has 'inade connect on loe-I tween the cord circuit thereat and theeentral f oflice endofthe' trunk circuit, and has projec-ted "ringing; current out over the triink circiiit to cause the 'opera'tion'of call. bell 15',

ivhich'in the'system' illustrated in. the draw ing is shown associated With'station'A' of 1 the intercon nnnnicating systen' This stationf A therefore servesas the answering stamon of the intercommnnicatinrj systeln so far as: 5 1ncon lllig calls over "the trunk 'cireuit are? removes the reeeiverjt'rW the svvitchhookl 'Upon- =thedepre 'ronofthe rnnk answering v key T at; station-A and the I rein'oval of the 85 'tOYGEtI ISB the deenergizationiioif itlie difieren 7 tialrelay 8 to remove the .holdingbridgefi I In the drawing thereis shown atrnnk" i circuit comprising conductors 51 and 6," vwhich extends-to a central oflice, not shown, This trunk circiiit is multipled'to the various;

is then depressed.

through the alternate contact of relay 10,

I to

individual; key 2.

contact of holding key H, and the lefthand winding of differential relay 8 to ground.

The differential relay 8, in being energized, attracts its arinatures; thereby establishing a locking circuit for itself from battery through its middle alternate contact and left'hand winding to ground.- The attrac-.; tionoi the -'r1ght-hand;armature of relay 8 connects the holding bridge? across the conductors 5 and 6 of the trunk circuit, so that i this bridge 'Z re1nain s. substituted for the telephone sctof station A after the trunk answering key T of station A is restored to normal*position by the depression of the trunk answering key T to n'ornial position,

tollowing ithe depression of the individual kev opens the circuit oi: relay 10, which 1 L thereupon releases, ltelay 9 isthereby actuated over a circuit from battery'through the normal contact of relay 10, left-hand alter- V nate contact of dliferentiai relay 8 and-the windingoirelay 9. to ground, Relay'El, in operating completes; a locking circuit tor itself from battery throughthe mic dle alternatecontact ofdiilerential relay 8, lett-hand alternate contact of relay 9 andthe winding -thereof to ground; The closure of the rightcontact of relay 9 prepares a circuit for the right-hand winding of differential relay 8.

'The attendantIat station A rafter actuating the dividual key 2 then depresses the ring ing key 3-, thereby causing the operation of the signaling device-17 at station B over a circuit from battery through this signaling device 17, contact l8 controlled'by-th'c switchhook'oif the telephone set, conductors 19 and 20, contact Ql of individual; key 2 and the alternate contactof ringin'g key R to ground. The partyat station Bgin response to the actuation of the signaling device 17, depresses the local answering key L and removes the' receiver froin'the switchhook thereby connecting the telephone set of station B inaeircuit with the telephone set of station A, Talking battery for the telephone set at station B is furnished frointhe talling' battery TB over; conductor 25, through the left-hand winding OfIBtZtl'ClfltlOIl coil 26,

I contact 27 of the local answering key L,the

transmitter, switchhook contact and the winding of the induction coil of the telephoneset at station B, contact28 of the local The restoration of the,

ductors 19 and 20, contact 21 of key 2, nornial contact of ringing key R at station A, the transmitter, the .svvitchhoolc contact and winding of the induction coil of the telephone-set at station: A, contact 32 of key 2, conductors 33 and 34, the right-hand winding of retardation coil 26, and conductor 29 back tothe battery TB. Afterthe attendant at station A has adyised the party at station B that the incoming call is for station B, the v attendant-restores the receiver to the switchhook and the party at station B depresses the trunk answering button T, thereby restoring the localbanswering key L to normal position. The restoration of the iocal answering key L1 to normal" position 1 disconnects the telephoneset of stationB from station A, and thedepression of the trunk answering key T connects this. telephone set of station Brwith the trunk circuit, 5 Upon. the telephone set of station B being connected to the trunk circuit,.a circuit includingrelay 10 is established, whereupon this relay attracts its arin 'tures. The at tractlo'nci the armature of relay l0 cornplet a circuit v for the right-hand winding of (ll' erential relay Swlnclrinay be traced from battery through "the alternate contact 7 oi relay 10; light-hand contact olrelay 9;

and the right-hand winding of difiierential relay 8 to ground. Current now traverses both windings of the difl'erential relay 8, and since this relay is differentially wound, the magnetization produced by one winding neu- T tralizes thatproduced by the other, and the relay releases its jar-matures,whereupon the holding bridge 7 LlSJTQI HOVQd flOfi] the trunk circuit and relay 9 released. Upon the conclusion of the eonversationover the trunk circuit the party at stationB restores there ceiver to the switchhook, whereupon relay 10 releases its earrnatr and the usual supervisor-y rel ayof the cord circuit at the central office (not shown) is released'to cause the lighting of the usual supervi.

lamp (notsliown). v i 7 From the above descriptionit vwill be ap parent that this invention'proifides a'systen'i in which there is no chance that the trunk circuit will be momentarily opened while. an incoming call over the trunk 1 ry disconnect with the first relay when subsequently energizedto cause the release of the second I relay. V

set at each station adapted to be connected with the trunk circuit, a bridge for holding the trunk circuit in substitution ofthe telephone set, a relay in the trunk circu'itlener- 7.]In a telephone system, in combination, 7 a plurality of subscr1bers"stat1ons, a trunk circuit multiple d to thestations, a telephone gized upon theconnection. of the telephone set thereto. a he :asecondirela controlled. 7

V by said keywhile the first relay isenergized -tion of the,brid-ge'V-connecting relay, means to connect the bridge across the trunk cir- *cuit, a third. relay operating upon the-deenergization of the first relay, and a disabling circuit for the second relay includ ing contacts o'Ethe first and third relays established upon the-reenergization of the qfirstrelayl and the energization of the third relay to cause ,the release of the second relay.

setjat each stationadapted to be connected with the trunk circuit,"a bridge for holding the trunl ucircuit in substitution of a telephone set, a relay when energizedconnecting the. bridge across the trunk circuit, a relay in the trunk circuit energized upon the connection of the telephone set-with the trunk circuit, a switch coiiperating with the energized trunk rela-y to cause the energrzation of the bridge-connecting relay, and means independentjot the switch actuated" subse quent to the connection of the bridge with" the trunk circuit to disconnect the telephone set therefrom. ;1

In a teleplione system, in combination, a plurality of subscribers stations, a V trunk circuit inultipled to the stations, a telephone set at' each station adapted to be connectedfwiththe trunk circuit, a bridge for,

holding the trunk circuit injsubstitution oi a telephone set, a relay when energized connecting the bridge across the trunk circuit, a relay in the trunk circuit energized upon the connection of. the telephone set with the trunk circuit, a switch cotiperating with the energized. trunk relay to cause the energize independent otthelswitch actuated subsequent to the connection of the bridgeqwitlr i the ,trunk circuit todisconnect the telephone setgthereirom, and a disabling circuit for the bridge-connecting relay established upen the subsequentenergization of the trvnkrelay by the connection of the'telephone set with the trunk circuit whereby'the bridge is disconnected therefrom.

10. In a telephone system, 111 combination,

"a plurality of subscribers. stations, a trunk I circuit multipled to the stations, a telephone setateach station, a'switchat each station 8. In a telephonesystem,,in co nbinatiom, a plurality of subscribers stations, a trunic OllfQlllilIllllltlPlGCltO the stations, a telephone the cnergization 1. of the bridgeconnecting relay, and means independent of the lastmentionedswitch actuated subsequent tothe 'ing with the energized trunk relay to cause,

connectionof the bridgevjwith the trunk cir-V' cuit to disconnect. thetelephone set therefrom,

11. 111 a telephone system in CQIllblllitlJlOlh; .a plurality ofsubscr bers stations, a trunk circult multipled to the stat1ons,a telephone set at each station, a switch at each station controlling the connection of the telephone set thereat with the trunk circuit, a bridge :i'or holding the trunltcircuit in substitution tor a telephone set, a. relay for connecting the bridg'eacross the trunk circuit, a relay in the trunk circuit energized upon the connection or thetelephone set therewith, a

switch momentarily-actuated and cooperat- 111g wlth the energized trunk relay'to cause the energization of the bridge-connecting re lay, means independent of the last-mentioned switch actuated subsequent to the con.- nection of thebridge with the trunk circuit to disconnect, the telephone. set therefrom,

, and arlisabling circuit for the bridge-cone nect ng relay'cestab hshed upon the subse: quentenergizat on of the trunk relay due to.

the con'nectionfiof the telephone set with the trunlccircuit whereby the bridge is disconnected therefrom. V

12 In a telephone system, in combination, a plurality of subscribers stations, a trunk circuit multipled to the stations, a telephone set at each station adapted to be connected with the trunk circuit, a locking key at each station controlling the connection of the telephone set thereat w th the trunk circuit, a bridge for holding thetrunk circuit in -substitution of a telephone set, a'relay when en-j .ergized connecting the bridge across the 1 trunk clrcult, a relay n the trunk circuit energized while a telephone set is connected therewith, a non-locking key cooperating when actuated wlth the energized trunk relay to cause the energization of the bridgeconnecting relay, a locking circuit fer the brldgeconnectmg relay established upon its energization, and means actuated subsequent to the connection of the ln-idge with 1 the trunkcircuit to disconnect the telephone set therefrom. v

13. In a telephone system, in combination, I a plurality of subscribers stations, a trunk circuit multipled to the stations, a tele-v phone; set at each station adapted to be connected with the trunk circuit, a locking key when energized connecting the bridge across the trunk circuit, a relay in the trunk circuit energized while a telephone set 1S-COI1Il6Ct6Cl therewith, a non-locking key cooperating when actuated with the energized trunk relay to cause the energization of the bridgeconnecting relay, a locking circuit forthe bridge-connecting relay established upon its energization, means actuated subsequent to the connection of the bridge with the trunk circuit to disconnect the telephone set therefrom, and a disabling circuit for the bridgeconnecting relay established upon the subsequent energization of the trunk relay due to the connection of the telephone set with the trunk circuit whereby the bridge is disconnected therefrom. V

14. In atelephone system, in combination, a plurality of subscribers stations, a trunk circuit multipled to the stations, a telephone set at each station, a locking key at each station controlling the connection of the telephone set thereat With the trunk circuit, a bridge fol-holding the trunk circuit in substitution of a telephone set, a relay in; y

the trunk circuit, a'relay for connecting the v bridge across the trunk circuit, a non-lock ing key, an energizing circuit for the bridgeconnecting relay completed upon the momentary actuation of the non-locking key When the trunk relay is energized, a locking circuit for the bridge-connecting relay established upon the energization thereof,

and a disabling circuit for the bridge-connecting relay established upon the subse quent energization of the trunk relay due to the actuation of one of the locking keys.

In witness whereof I hereunto subscribe my name this 19th day of September, A. D."

WALLACE PL. ANDRIGK. 

